Issue #20616: Add a format() method to tracemalloc.Traceback.

Lib/tracemalloc.py

@@ -1,6 +1,7 @@
 from collections import Sequence
 from functools import total_ordering
 import fnmatch
+import linecache
 import os.path
 import pickle
 
@@ -205,6 +206,18 @@ class Traceback(Sequence):
     def __repr__(self):
         return "<Traceback %r>" % (tuple(self),)
 
+    def format(self, limit=None):
+        lines = []
+        if limit is not None and limit < 0:
+            return lines
+        for frame in self[:limit]:
+            lines.append('  File "%s", line %s'
+                         % (frame.filename, frame.lineno))
+            line = linecache.getline(frame.filename, frame.lineno).strip()
+            if line:
+                lines.append('    %s' % line)
+        return lines
+
 
 def get_object_traceback(obj):
     """